Molecular weight regulation of ethylene-alpha-olefin copolymers

ABSTRACT

IN THE COPOLYMERIZATION OF ALPHAA-OLEFINS ESPECIALLY THE COPOLYMERIZATION OF ETHYLENE AND PROPYLENE (WITH A DIENE IF DESIRED), USING A COORDINATION TYPE CATALYST BASED ON A VANADIUM SALT AND AN ALKYLALUMINUM HAIDE, THE MOLECULAR WEIGHT OF THE POLYMER CAN BE REEGULATED, AND, IN SOME CASES, THE ACTIVITY OF THE CATALYST CAN BE ENCANCED BY ADDING CERTAIN DITJIOCARBAMATES. PHOSPHORODITHIOATES OR DITHIPCARBONATES. ELASTOMERS HAVING IMPROVED PROCESSABILITY CAN BE MADE IN THIS WAY. AS WELL AS ELASTOOERS WHICH ARE LIQUIDS AT AMBIENT TEMPERATURES AND WHICH ARE USEFUL AS ADHESIVE, SEALANTS, ETC.

United States Patent i 3,819,592 MOLECULAR WEIGHT REGULATION OF ETHYL- v ENE-ALPHA-OLEFIN COPOLYMERS Harry'Dale Visser, Cheshire, and Walter Nudenberg,

Newtown, C0nn., assignors to Uniroyal, Inc., New a York, N.Y. No Drawing. Filed Aug. 27, 1973, Ser. No. 391,902

-. Int. Cl. (108E 1/56, 1/34, 1/80 U.S. Cl. 26080.78 42 Claims ABSTRACT OF THE DISCLOSURE Thisinvention relates to' the preparation of ethylenealpha-olefin 'copolymerrubbers, especially ethylene-propylene copolymers, and more particularly it relates to the regulation 'of the'molecular weight of such rubbers.

Synthetic, rubbery ethylene-alpha-olefin copolymers are important and valuable materials, especially the unsaturated;sulfurrvulcanizable forms of such copolymers containing copolymerized thereina non-conjugated diene in addition to the ethylene and alpha-olefin. The invention is concerned with an. improvement in a highly preferred method-of making such copolymers, using a soluble catalyst based: onan alkylaluminum halide and a vanadium Salt-c2" 1,

, While such 'acatalyst system has many advantages, nevertheless it has been desirableto improve still further the polymerization method. In particular, it has been desirable to provide a way of regulating the molecular weight of the polymer, so that a material of lower molecular weight and easy processability can be obtained. In anionic coordination polymerization, the molecular weight of the polymer produced is usually high, frequently too high even for conventional applications as a rubber, e.g. too high molecular weight for good mill processability) The molecular .Weight can usually be varied to some degree by changing polymerization parameters, such as catalyst and cocatalyst type, catalyst concentration, concentration of monomers and polymerization temperature. The magnitude oflthe molecular weight reduction obtained from these changes is usually rather small, and in addition the yield and quality of the product is often adversely affected. Another way. of reducing the molecular weight involves the use of a so-called molecular weight regulator which, when added'to the polymerization, reduces the molecular weight, hopefully without having any adverse effect on the quantity or quality of the polymer product. There are basically two factors which govern the degree of molecular weight regulation attainable from a given molecular weight regulator. The first factor is the regulator type. Some regulators, by virtue of their mode of operation, are simply more eflective than other regulator types. The second factor is the concentration at which the regulator can-be used. Some regulators tend to shortstop the polymerization when used at high levels, while other, like hydrogen, can -be used at extremely high levels without any adverse effect on the polymerization. This latter fact enables one to obtain a high degree of regulation from hydrogen. Liquid ethylene-propylene copolymers can be made using this type of approach as described in Netherlands Pat. 6803332, Sun Oil Co., Mar. 8, 1967. A similar system was also used to make the so-called near liquid," low molecular weight ethylene-propylene-dicyclopentadiene copolymers. This invention provides novel, unusually powerful regulators, and makes possible the production of truly liquid copolymers, including both terpolymers and binary copolymers.

The regulators of this invention can be used by themselves or may be used in combination with a second regulator such as hydrogen. With certain catalyst systems this modifier/hydrogen combination is particularly efiective as a regulator. The bulk of the molecular weight regulation obtained from this type of combination results from the regulator and not from the hydrogen but the hydrogen can be used to achieve further regulation or reduction of molecular weight and also, in some cases, improvement of catalyst efficiency.

Organometallic compounds such as diethylzinc or diethylcadmium have been disclosed as regulators (British Pat. 889,852, Montecatini, July 26, 1960 and British Pat. 902,845, Shell Research, Ltd., June 2, 1960). These compounds are, however, expensive, and difficult to handle due to their pyrophoric nature. These difiiculties can be overcome by the use of metal complexes such as cobalt (III) acetylacetonate (US. Pat. 3,462,399, D. N. Matthews, Aug. 19, 1969) or zine acetylacetonate (Canadian Pat. 864,629, B. F. Goodrich, Aug. 2, 1968). The metal complexes employed in this invention differ from those mentioned above in that they are sulfur-based rather than oxygen-based metal complexes and are commonly known to those in the art as sulfur vulcanization accelerators. Certain organic and inorganic sulfur compounds have been demonstrated to possess molecular weight regulating ability; in fact, sulfur itself is an activator/regulator (US. Pat. 3,377,325, F. C. Loveless, Apr. 9, 1968). Alkyl disulfides are also regulators (US. Pat. 3,462,399, D. N. Matthews, Aug. 19, 1969).

According to the present invention, it has been found that certain sulfur vulcanization accelerators are capable of regulating the copolymerization of ethylene and another alpha-olefin, with or without a copolymerizable polyene, by the conventional soluble catalyst system based on an alkylaluminum halide and a vanadium salt. More particularly, the invention is based on the discovery that certain (a) phosphorodithioates, (b) dithiocarbamates, and (c) dithiocarbonates are effective regulators of the copolymerization.

It is to be emphasized that the catalyst system employed in the invention is of the soluble kind (i.e., soluble in the monomers and/or in the usual solvents used as polymerization media, e.g., hexane), as distinguished from insoluble or heterogeneous catalyst systems. The alkylaluminum halide that forms the catalyst system along with the vanadium salt may be a dialkylaluminum halide, a monoalkylaluminum dihalide or an alkylaluminum sesquihalide, where the alkyl group can have from 1 to 10 carbon atoms, such as a methyl, ethyl, propyl, etc. The halogen in these alkylaluminum compounds is usually ch10 rine, although bromine or other halogen may be used. Among the vanadium salts which may be used are vanadium halides, oxyhalides, alkoxides and acetylacetonates. Specific examples of these compounds are vanadium trichloride, vanadium tetrachloride or bromide, vanadium oxydichloride, vanadium oxytrichloride, trialkyl vanadates (especially where the alkyl group contains 1-12 carbon atoms, e.g. tri-n-butyl vanadate), 'vanadyl or vanadium acetylacetonate, and the like, as well as compounds based on mixtures of more than one of the foregoing types, such as dialkyl halovanadates (e.g. dibutyl chlorovanadate) and alkyl dihalovanadates (e.g. butyl dichlorovanadate). In many cases the preferred vanadium salts are vanadium oxytrichloride, vanadyl or vanadium acetylacetonates, lower trialkyl vanadates (where the alkyl groups contain 1-4 carbon atoms) and halovanadates, especially chlorovanadates(mono and dichloro). As in conventional practice, the molar ratio of aluminum to vanadium is ordinarily at least 4:1 and usually about :1; higher ratios such as :1, 35:1, or even higher, may be used. If desired, very high ratios of aluminum to vanadium (e.g. 200:1 or higher) may be employed, especially in those cases where the concentration of the vanadium salt is very small. Conventional catalysts of this kind are de scribed in U.S. Pat. 3,547,855, Loveless, Dec. 15, 1970.

The sulfur vulcanization accelerators which can be used as regulators in the present invention may be (a) a phosphorodithioate, of the following formula:

(b) a dithiocarbamate of the formula :(c) a dithiocarbonate of the formula Considering first the phosphorodithioates (a), R and R in the stated formula can be the same or different and can be, for example, an alkyl group (such as methyl, ethyl, butyl, hexyl, octyl, dodecyl or octadecyl), a cycloalkyl group (such as cyclopentyl, cyclohexyl or cyclooctyl), an aryl group (such as phenyl, tolyl, Xylyl, nonylphenyl, naphthyl), an aralkyl group (such as benzyl, phenylethyl, phenylbutyl or naphthylethyl), or the like. The R and R need not be separate distinct organic groups but can also constitute a diradical, such as trimethylene, 2,2-dimethyltrimethylene, tetramethylene, or pentamethylene. Y may be a metal atom from Groups I-2B (copper, silver, gold), II-lB (zinc, cadmium, mercury), III- B (scandium, yttrium) IVB (titanium, zirconium, hafnium, V- B (vanadium, niobium, tantalum), VI-B (chromium, molybdenum, tungsten), VII-B (manganese, technetium, rhenium), VIII-B (iron, cobalt, nickel), III-A (aluminum, gallium, indium, thallium) and IVA (germanium, tin, lead) in the Periodic Chart, while n of course depends upon the valence state of the particular metal atom in question. In the case of these phosphorodithioates Y can also be hydrogen, as in 0,0-diethyl hydrogen phosphorodithioate, '0,0-diisopropyl hydrogen phosphorodithioate, and 0,0-2,2-dimethyltrimethylene hydrogen phosphorodithioate. Some examples of metal phosphorodithioates are zinc 0,0diethyl phosphorodithioate, zinc 0,'O-dipentyl phosphorodithioate, chromium (III) 0,0-diethyl phosphorodithioate, nickel (II) 0,0-diethyl phosphorodithioate, cobalt (III) 0,0-diethyl phosphorodithioate, copper (-II) 0,0-diethyl phosphorodithioate, zinc 0,0'dineopentyl phosphorodithioate, zinc 0,0-dicyclopentyl phosphorodithioate, zinc 0,0-dicyclohexyl phosphorodithioate, zinc 0,0-dibenzyl phosphorodithioate, and zinc 0,0-diphenethyl phosphorodithioate.

The preferred type (a) regulators are the zinc salts; however, the zinc salt need not be added to the reactor as a distinct entity, but can be prepared in situ by reacting a non-regulating zinc salt such as zinc stearate or a zinc halide with an 0,0-disubstituted hydrogen phosphorodithioate such as 0,0-diethyl hydrogen phosphorodithioate.

Regarding the dithiocarbamate regulators of formula (b), R, R and n in this type may be as previously defined for the phosphorodithioates (a), and Z may be a metal atom as defined in case (a). Some typical examples of type (b) are zinc N,N-dimethyl dithiocarbamate, zinc N,N-dibutyl dithiocarbamate, zinc N-n-octadecyl-N-iso: propyl dithiocarbamate, iron (III) N-n-octadecyl-N-is'opropyl dithiocarbamate, copper (II) N-n-octadecyl-N-isopropyl dithiocarbamate, chromium (HI) N-n-octadecyl-N- isopropyl dithiocarbamate, nickel (II) N-n-octadecyl-N- isopropyl dithiocarbamate, nickel (II) N,N- dibutyl dithiocarbamate, zinc N,N-pentamethylene dithiocarbamate, zinc N-ethyl-N-phenyl dithiocarbamate, andzinc N,N-dibenzyl dithiocarbamate. Some of these metal dithiocarbamates with short'chain alkyl groups tend to be not as soluble'as would be desirable in non-polar hydrocarbon solvents, such as hexane or benzene. The solubility of these dithiocarbamates can be substantially increased by the use of a complexing agent such as pyridine, benzylarnine, or n-butylamine as reported by G. M. C. Higgins and B. Saville, J. Chem. Soc. 2817 (1963). These 1/1 complexes are at least equivalent to the uncomplexed parent dithiocarbamate compound in terms of regulating ability.

The preferred type (b) regulators are the zinc dithiocarbamates where the R and R are alkyl groups with 4-10 carbon atoms. I

In type (c), the dithiocarbonate type, R, Z, and n may be as defined previously. Some typical dithiocarbonates are zinc O-butyl dithiocarbonate, zinc Oethyl dithiocarbonate, zinc O-cyclohexyl dithiocarbonate, chromium (III) O-ethyl dithiocarbonate, and nickel (H) O-ethyl dithiocarbonate.

Depending upon the exact structure of the regulator and the degree of molecular weight regulation desired, these regulators are frequently used at a level of 0.05 to 5 times of the vanadium catalyst (on a molar basis). The preferred level usually lies between 0.5 to 1.5 times the molar concentration of the vanadium catalyst species. Some of the regulators employed in this invention such as O, O-2,2-dimethyltrimethylene hydrogen phosphorodithioate, are catalyst activators =(i.e. they increase the cata' lyst efiiciency) while others such as zinc 0,0-bis-4-methyl- Z-pentyl)phosphorodithioate or zinc N,N-dibutyldithiocarbamate, can function as activators under certain specific polymerization conditions, particularly polymerizations where very low catalyst levels are used. In addition to being regulators and activators, the regulators of this invention can, when used in conjunction with other regulators such as hydrogen or by an appropriate choice'of alkyl aluminum halide cocatalyst, give'either a very'narrow or a very broad molecular weight distribution (in other words, give molecular weight distributions broader or narrower than that obtained in the absence of any regulator).

One other factor that affects the processability of terpolymers is the extent of long chain branching. When a polycyclic diene is used as the termonomer there'is undesirable tendency for long chain branches'to form during the polymerization, with the result'that the elastomers are difficult to process. The poor processing of conventional cyclic diene types of EPDM (ethylenepropylene-non-conjugated diene terpolymer rubber") 'is manifested in excessively longmilling times required to form a continuous band on a rubber mill, poor extrusio'n characteristics, and the like. The improvement in processability (linearity) brought about by the presence of some of these vulcanization accelerators from the start of the terpolymeriz ation in accordance with the invention is manifested in significantly reduced milling time required to form a continuousband of the terpolymer rubber on a mill, with consequent economy, efiiciency and ease of compounding and shaping. The increased linearity (decreased long chain branch,- ing) of the product of the present process may be expressed as a number termed the branching index, which may in turn be calculated from measured values of the zero shear viscosity (see Tokita et al., Rubber Chemistry and Technology, Vol. 42, No. 2, June, 1969,

p. 944) and the intrinsic viscosity. The branching index, BI, is given by the expression B.I.=long (1 4.39 long (I.V.)5.06 where no is the zero shear viscosity (expressed as poises, measured at 130 C.) and I.V. is the intrinsic viscosity (expressed as deciliters per gram, measured in Tetralin at 135 C.).

Ethylene-propylene copolymers prepared by methods described herein are of particular interest as lubricating oil additives, especially as viscosity index improvers. Liquid or pseudo liquid terpolymers can be made using these molecular weight regulators of combinations of these molecular weight regulators and other conventional regulators such as hydrogen. These materials can be utilized as adhesives, sealants, caulking compounds or tackifiers.

In general the liquid elastomers cover a broad range of bulk viscosities. A liquid elastomer is often defined as one which can be pumped or poured at a reasonable temperature. In terms of measurable quantities this is usually taken to mean an elastomer with a Brookfield viscosity of 1500 poises or less at temperatures from room temperature (e.g., C.) up to 100 C. The synthetic One of the advantages of liquid elastomers (low molecular weight copolymers) is that the curatives can easily be dispersed into the compounded formulation by hand mixing or by some other simple mechanical mixing equipment. This advantage is most significant in cases where the curing system is operative at ambient temperature or some modest temperature above room temperature. EX- amples of such cure systems are the following: (a) quinone dioxime/PbO (b) h'alomethyl phenolic/ZnO; (c) accelerated sulfur; (d) quinone dioxime/N-haloamide (copending application Ser. No. 225,641, SJ. Cantor, filed Feb. 11, 1972); and (e) trihaloisocyanuric acid (copending application Ser. No. 325,907, Perkins, filed Jan. 22, 1973). Curable liquid ethylene-alpha-olefin-diene terpolymers can be utilized as adhesives, caulking compounds, sealants and plasticizing coagulants. The liquid terpolymers and the ethylene-alpha-olefin binary copolymers can also be used as tackifiers, plasticizers, or lubricants where curing is not a necessary requirement.

It will be understood that the present invention is applicable to the production of copolymers of ethylene and at least one other alpha-olefin (e.g., propylene, 1- butene, 1-octene, etc.), of the formula CH =CHR where R is an alkyl group of 1 to 12 carbon atoms, with or without at least one copolymerizable polyene, especially a diene, particularly a non-conjugated diene, whether an open-chain diolefin such as 1,4-hexadiene or a cyclic diene such as dicyclopentadiene, bicyclononadiene, the alkylidene norbornenes (e.g., 5-methylene-Z-norbornene, 5- ethylidene-Z-norbornene, 5-propylidene 2 norbornene), etc. Preferred terpolymers contain from about 1 to about 25% (more preferably about 2 to about 25 by Weight of a non-conjugated diene such as dicyclopentadiene or the like; the remaining portion of the terpolymer contains propylene (or other alpha-olefin) and ethylene in the weight ratio in the range from about 15/85 to about 85/15. Ethylene-propylene binary copolymers have the same weight ratio of propylene and ethylene as the terpolymers.

The polymerization is conveniently carried out in a solvent, although an added solvent is not essential; the monomers being polymerized can serve as the solvent. In general, the normal solvents for coordination anionic polymerization can be used. These include the aromatic hydrocarbons (e.g. benzene, toluene or xylene), aliphatic hydrocarbons (e.g. hexane or heptane), chlorobenzene, tetrachloroethylene,. and any other inert solvent which will not destroy the catalyst. The temperature is not-critical and may be as in conventional practice, e.g.,

'from 0 C. to C.

The procedure may otherwise be the same as in conventional practice as far as such details as type of polymerization equipment, pressure, concentration of catalyst, ratio of catalyst to cocatalyst, and the like, are concerned and may be carried out batchwise or continuously (see for example US. Pat. 3,341,503, Paige et al., Sept. 12, 1967). Incremental addition of ingredients may be employed. In a continuous polymerization the organoaluminum compound, the regulator and the vanadium compound may be added as separate feeds to. the monomer solution. In a batch polymerization a preferred procedure involves combining the organoaluminum compound and the regulator in the presence of at least a portion of the monomers and then adding the vanadium compound.

The following examples will serve to illustrate the practice of the invention in more detail.

Example 1 This example demonstrates the use of zinc 0,0-bis(4- met-hyI-Z-pentyl)phosphorodithioate as regulator. The reactor employed was a dry one-gallon glass autoclave equipped with a pressure gauge, thermometer, gas inlet tube, stirrer, rubber gasket for liquid injection, and an internal cooling coil attached to an external cooling source. Into this reactor were introduced 2500' ml. of dry n-hexane at 30 C., 15 mmoles of ethylaluminum sesquichloride (abbreviated as EASC) as a 25% by weight solution in hexane and 6 ml. of S-ethylidene-2-norbornene (abbreviated as ENB). Propylene gas was fed into the reactor to an internal pressure of 30 p.s.i.g. at a temperature of 30 C. The pressure was then brought to 50 p.s.i.g. by feeding ethylene. Then 027 ml. of zinc 0,0-bis(4-met-hyl-2-pentyl)phosphorodithioate was added; this amount represents 0.6 mmole. Next, 2.0 mmoles of vanadium oxytrichloride was added as a 10% by volume solution in hexane. An additional 2 ml. increment of ENB was added to the reactor 10 minutes after the vanadium oxytrichloride addition. The reaction was allowed to proceed for 30 minutes while maintaining the temperature at 30 C. and the pressure at 50 p.s.i.g. by feeding ethylene and propylene at a 1/1 molar ratio. After 30 minutes the polymerization was terminated by the addition of 2 ml. of polypropylene glycol (molecular weight about 2000). The terpolymer was precipitated by adding the reaction mixture to 3000 ml. of isopropanol containing 0.4% by weight of 2,2-methylenebis(4-methyl-6-t-butylphenol) antioxidant. The polymer was dried overnight under vacuum at 40 C. The yield was 86.4 grams of polymer containing 47% propylene by weight; iodine number 13.6; intrinsic viscosity 1.39 (all intrinsic viscosities herein are expressed as deciliters per gram in Tetralin at C.), branching index 0.89.

Repetition of the example without the zinc 0,0-bis(4- methyI-Z-pentyl)phosphorodithioate additiongave 105.5 grams of terpolymer containing 46% propylene by weight; iodine number 14.7; intrinsic viscosity 2.74, branching index 1.56. This example is summarized in Table I, along with other examples where the A columns represent the control without zinc 0,0-bis(4-methyl-2-pentyl)phosphorodithioate (designated Regulator R1 is Table I) and the B columns represent the practice of the invention.

Examples 2 and 3 7 Example 4 Examples and -6 Examples 5 and 6 demonstrate the use of nickel (II) and chromium (III) '0,0-diethyl phosphorodithioates as regulators (designated Regulator R2 and R3, respectively tively, in Table I) with EASC as the cocatalyst using the experimental procedure of Example 1. Both of these compounds act as regulators of the molecular weight of the terpolymer system. The results are shown in Table I.

8 phosphorodithioate, and R12 is 0,0-diethyl hydrogen phosphorodithioate.

Example 18 This example describes the in situ preparation of a 5 zinc 0,0-dialkyl phosphorodithioate and its use as a regulator. The procedure was similar to the previous example (i.e., Example 17) except that in addition to the 0,0-diethyl hydrogen phosphorodithioate regulator, 0.63 gram of zinc stearate was also added to the reactor prior to the vanadium oxytrichloride injection (this is indicated as Regulator R13 in Table III). Table III lists the data from this polymerization run under the column heading 18A. The degree of regulation attained in this example, as measured by intrinsic viscosity, was substantially greater than that of the previous Example 17 but comparable to that obtained from zinc 0,0-bis(4-methyl-2- pentyl)phosphorodithioate (Regulator R1) at the same level, as shown in column 188 of Table III. Zinc stearate itself (Regulator R14), even at very high levels has no TABLE I.REGULATION OF EP COPOLYMERIZATION WITH PHOSPHORODITHIOA'IE Example A B A B A B A B 5 6 Cocatalyst (mmoles of aluminum):

DIBAC- 50 50 Catalyst (mmoles): V0013 2.0 2.0 2.0 2. 0 2. 0 2. 5. 0 5.0 2.0 2.0 Diene ENB ENB DCPD DCPD None None ENB ENB ENB ENB Regulator (mmoles):

0.64 Yield, g- 105. 5 86.4 95. 1 86.3 90.0 58. 0 109. 6 77. 8 79.3 66.0 Iodine number 14. 7 13. 6 8. 6 16. 3 18. 7 8. 3 16. 0 Propylene, wt. percent- 46 47 47 39 48 5O 56 45 43 44 I.V 2.74 1.39 2.76 1.91 2.56 1.35 3.29 1.89 2 16 2.34 Branching index 1. 56 0. 89 3. 00 1. 92

Examples 7, 8 and 9 efiect on the intrinsic v1scos1ty as shown by the data in Examples 7, 8 and 9 are illustrations of the use of zinc N,N-dibutyl dithiocarbamate as a regulator (designated Regulator R4 in Table II) following the procedures of Examples 1, 2 and 3 respectively, except that the zinc 0,0-bis(4-methyl-2-pentyl)phosphorodithioate (R1) is replaced by zinc N,N-dibutyl dithiocarbamate (R4). The data is summarized in Table H.

Examples 10-14 (II) N-n-octadecyl-N-isopropyl dithiocarbamate and R9 55 is cadmium N,N-dibutyl dithiocarbamate.

column 18C of Table III. 1

TABLE III.REGULATION OF EP COPOLYMERIZATION Example 15 16 17 A B C Diene ENB ENB ENB ENB ENB ENB Regulator R10 R11 R12 R13 R1 R14 Regulator (mmoles) 2. 0 3. O 2. 0 1. 0 1. 2 7. 1 Yield, g 114. 2 113. 8 82. 8 114. 0 82. 3 66. 8 Iodine number 10. 4 9. 9 12. 3 7. 5 16. 3 16.5 Propylene, wt. percent- 44 49 46 40 39 LV 2. 35 1.81 2. 04 0.69 0.83 2. 59

50 Example 19 This example illustrates the use of 0,0-2,2-dimethyltrimethylene hydrogen phosphorodithioate as a catalyst activator. The technique of mixing the primary catalyst components (i.e. the EASC and VOCI in the absence of the polymerizing monomers was used to accentuate the TABLE IL-REGULATION OF EP COPOLYMERIZATION Example A B A B A B 10 11 12 13 14 Diene ENB ENB D CPD D CPD None None ENB ENB ENB ENB ENB Regula r R4 R4 R4 R5 R6 R R9 Regulator (mmoles) 0. 35 0. 0. 2. 0 2. 0 1. 0 1. 0 1. 0 Yield, 105. 5 101. 1 95.1 78.5 0 109. 6 75. 5 63.7 63. 9 86. 8 90. 0 Iodine number 14. 7 10. 7 8. 6 7. 8 13. 6 16. 3 14. 7 11. 8 13. 4 Propylene, wt. percent. 46 43 47 48 I. 2. 74 1. 79 Branching index 1. 56 0.

Examples 15-17 Examples 15-17 set forth other compounds which function as regulators according to the method of this invention. In these examples the procedure was substantially the same as in Example 1. The results are listed in Table III, wherein Regulator R10 is zinc O-butyl dithiocarbonate, R11 is 0,0-2,2-dimethyltrimethylene hydrogen Example 16 except for the amount of and manner of addition of the catalyst components. The EASC (15 mmoles) 75 and VOCl (3.0 mmoles) were mixed together in a separate flask in the absence of the monomers and aged for 6 hours. This premix or a'ged catalyst solution was then added to the reactor which already contained the hexane solvent, the ethylene and propylene monomers, the ENB, 'and the 0,0-2,Z-dimethyltrimethylene hydrogen phosphorodithioate activator. The polymerization was run for 3 minutes, and worked up in the usual manner. The yield was 66.5 grams, iodine number 11.5, intrinsic viscosity 2.02, and weight percent propylene 42.

In a similar experiment without 0,0-2,2-dimethyltrimethylene hydrogen phosphorodithioate, where the catalyst component was aged only 3 hours, the yield was only 35.5 grams, with an iodine number of 13.9, I.V. at

Examples 20-27 The ability of the present regulators to reduce the molecular weight permits the use of lower levels of VOCl while still obtaining a polymer which is suitable for end use applications as a rubber. The use of lower catalyst levels is also inherently more efiicient (efiiciency being defined as the number of grams of polymer obtained per gram of V0Cl catalyst). The regulators employed in this invention are particularly eifective in enhancing the efficiency at these lower catalyst levels. The supporting data is shown in Table IV, wherein R1 is zinc 0,0-bis(4- methyl-Z-pentyl)phosphorodithioate and R4 is zinc N,N- dibutyl dithiocarbamate.

The experimental procedure used in these examples was the same as in Example 1 except that the catalyst, cocatalyst, and diene (ENB) charges were varied as outlined in Table IV.

TABLE IV.-ACTIVATING EFFECT OF REGULATORS Example 20 21 22 23 24 25 26 27 EASC (mmoles 15 7. 5 7. 5 5 7. 5 5 V0013 (mmoles) 2.0 1.0 .5 2. 0 1.0 .5 1.0 .5 EN B (mls.):

Initial eharge-.-.-..- 8 5 4 8 5 4 5 4 10 min. charge..-. 3 2 1. 5 3 2 1. 5 2 1. 5 R1 (mmoles) 1.2 .6 .3 R4 (mmoles) 21 105 ield, g 105. 5 66 0 47 5 82. 3 72.0 64. 8 84. 5 51. 6 Efficiency- 305 381 548 238 415 748 487 596 2. 74 3. 3. 54 83 91 1. 51 1. 51 2. 11

Iodine number Examples 28, 29 and 30 Using a procedure similar to that outlined in Example 1 three ethylene-propylene-ENB terpolymers were prepared in a larger reactor such that a suflicient amount of polymer was made available for a general evaluation of vulcanizate properties. These polymers were made with zinc 0,0 bis(4 methyl 2-pentyl) phosphorodithioate (Regulator R1 in Example 28, Table V) zinc N,N-dibutyl dithiocarbamate (Regulator R4 in Example 29, Table V) i and hydrogen modified EASC/VOCl catalyst system (Example 30, Table V). Since it was desired to provide Uthese terpolymers in relatively high molecular weight form, as compared with the earlier examples, a much lower catalyst level (i.e. V001 concentration of 0.13 mmole per liter versus 1.1 mmole per liter as used in Examples 1 to 18). Examples 28, 29 and 30 also differed from the previous examples in that the polymers were isolated by steam flocculation rather than alcohol flocculation. T o evaluate the polymers in a heavy service tire tread stock formulation, 100 parts by weight of polymer was mixed with 40 parts carbon black (ASTM No. N-285 type), 5 parts zinc oxide, 1 part stearic acid, 1 part N-cyclohexyl-Z-benzothiazole sulfenamide, and 2 parts sulfur. The results of the'evaluation are shown in Table V. Both terpolymers using the regulators of the invention (Examples 28 and 29), exhibited fast curing properties, giving a good cure in 10 minutes at 320 F.

TABLE V.TIRE TREAD STOCKS Example Regulator R1 R4 Hydrogen Polymer properties: I

I.V 3.31 1. 98 1. 91 Propylene, wt. percent 42 46 44 Mooney viscosity, ML-4 at 212 94 99 102 Iodine number 11. 0 13.0 12.5 Compound properties:

Monsanto Rheometer:

130 114 121 20 8.5 8. 8 4. 0 4. 3 5. 0 28 31.5 30 Cured prope 10 min. at 320 F.:

Tensile, p.s.i 3,830 1,710 2,130 300% modulus, p.s.i. 1, 090 990 840 Elongation percent.... 560 390 470 Hardness, hore A... 65 63 64 30 min. at 320 F.:

Tensile, p.s.i 2,870 2,410 1, 660 300% modulus, p.s.i 2,140 1,830 1,830 Elongation percent. 320 340 250 Hardness, hore A.... 68 68 68 Examples 31 to 36 Some of the regulators of this invention are especially suitable for preparing liquid copolymers having molecular weights as low as 1500 (IV. of about 0.10). The specificity with respect to liquid copolymers depends on the particular catalyst components. Outstanding results are obtained with vanadium oxychloride and vanadium acetonylacetonate with the latter as the preferred catalyst along wkith alkyl aluminum sesquichloride and zinc phosphorodithioates as the molecular weight regulators.

This example demonstrates the synthesis of liquid ethylene-propylene-ENB terpolymers using zinc O,O-bis- (4-methyl-2-pentyl)phosphorodithioate as the regulator. The reactor employed was equipped with a pressure gauge, thermometer, gas inlet tube, stirrer, rubber gasket for liquid injections, and an internal cooling coil attached to an external cooling sources. Into this reactor were introduced 2500 mls. of dry n-hexane, 15 mmoles of ethylaluminum sesquichloride (abbreviated as EASC) as a 25% by weight solution in hexane, 1.35 mls. of zinc 0,0- bis(4-methyl-2-pentyl)phosphorodithionate and 8 mls. 0f 5-ethylidene-2-norbornene (abbreviated as ENB). Propylene gas was fed into the reactor to an internal pressure of 30 p.s.i.g. at a temperature of 30 C. The pressure Was then increased to 35 p.s.i.g. with hydrogen and finally brought to 50 p.s.i.g. with an ethylene. Next, 3.0 mmoles of vanadium oxytrichloride was added as a 10% by volume solution in hexane. An additional 3 mls. increment of ENB was added to the reactor 10 minutes after the vanadium oxytrichloride addition. The reaction was allowed to proceed for 30 minutes while maintaining the temperature at 30 C. and the pressure at 50 p.s.i.g. by feeding ethylene and propylene at a 1/1 molar ratio. After 30 minutes the polymerization was terminated by the polymerization was terminated by the addition of 2 mls. of polypropylene glycol (molecular weight about 2,000). 1.5 gms. of 2,2'-meth ylene bis(4 methyl-6-t-butylphenol) antioxidant was added to the polymer solution. The solution volume was then reduced to about 700 mls. total by vacuum distillation techniques. This concentrated liquid EPDM cement was then washed with 500 mls. of an aqueous polyetherdiamine solution for catalyst removal following the procedure of US. Pat. 3,547,855, F. C. Loveless, Dec. 15,

1 1 1 2 higher molecular weight polymer whose analytical and conjugated diene, in solution in an inert organic solvent polymerization data is listed as Example 32 of Table VI-.-- in the presence of a vanadium salt-alkylaluminum halide Repetition of Example 31 without the hydrogen addianionic coordination polymerization catalyst-which is sole tion but where the initial propylene loading was 33 p.s.i.g. uble in said solvent, the improvement comprising carrying followed by an ethylene feed to 50 p.s.i.g. gave a similar 5 out'the said polymerization'in the presence of, a regulator polymer to that of Example 31 but slightly higher in moselected fromthe group-consisting of Y a lecular weight. The datafor this polymer is listed as Ex: (a) a phosphonodithioate of the formula ample 33 in Table VI. a r Y Example 34 is a repetition of Example 31 in which the zinc 0,0-bis(4-methyl-2-pentyl)phosphorodithioate a vs v as well as the hydrogen were eliminated. The properties ,{l Y of this terpolymer are given in Table VI. I p V I Example 35 and 36 illustrate the use of zinc 0,0-bis- R v (4-methyl-2-pentyl)phosphorodithioate in the preparat tion of ethylene-propylene-dicyclopentadiene (abbreviated as DCPD) and ethylene-propylene-1,4-hexadiene co- Whereln R and are alkyl, y y y a a y polymers (abbreviated as 1,4-H) respectively. The proor are connected togetheras a polymethylene chain,

cedure was identical to that of Example 31 with the ex- Y 15 hydrogen-era metal of Groups IB VI If ception of the diene. The results are summarized in IIIA or IV-A, nd i1 3 a u r equal'to the val- Table VI. enceofY, 1

TABLE VI.--LIQ,UID TERPOLYMERS Example 31 32 33 34 35 36 Diene ENB ENB ENB ENB DCPD 1,4-H

Zinc 0,0-bis(4-methyl-2-pentyl)phosphorodithioate (mmoles) 3 3 3 3 Hydrogen, p.s.i.g 5 5 5 Yiel g 149 280 149 143 117 89 Propylene, wt. percent. 46 33 53 49 41 46 Iodine number 8 8 11 0 10.5 18.5 7.0 8.0 Intrinsic viscosity 32 1. 48 .40 2. 28 27 Mooney viscosity, ML-4 at 212 F 43 150 Molecular weight, Mn 5,400 5,320 5, 5, Brookfield viscosity at 60 0., pnises 1, 404 5,588

These examples demonstrate the use of vanadium (b) a dithiocarbamate of the formula acetonylacetonate as the preferred catalyst along with R S aluminum sesquichloride and zinc phosphorodithioate as 35 II z the molecular weight regulator. This system is especially useful for the preparation of very low molecular Weight a I terpolymers. wherein R and R are as previously defined, Z is a EXamPIeS 37, 33 and 39 are ethylene-pfopylene-ENB metal as previously defined for Y, and m: is'a numliquid terpolymers made using the procedure of Example b equal t th v l f id m t l, d 31, the only difference being the catalyst. Example 37 1s a di hi b t f th f m l the control, run without any hydrogen and zinc phos- S phorodithioate. Example 38 was made using zinc 0,0- l: 1| :lz bis(4-methyl-2-pentyl) phosphorodithioate as the sole m 7 molecular weight regulator. Example 39 was made using where R, Z and m are as previously defined, I the combination of zinc phosphorodithioate and hydrogen whereby the molecular weight of the resulting coplymer as a molecular weight regulator. Examples 40 and 41 are is regulated. analogous to Examples 37 and 38 with the exception that 2. A method as in claim 1 in which the said copolymer no termonomer was used. Examples 42 and 43 are analis a saturated ethylene-propylene binary copolymer. ogous to Examples 37 and 38 using dicyclopentadiene as 3. A method as in claim 1 in which the said copolymer the termonomer. is an unsaturated ethylene-propylene-non-conjugated di- As can be noted from the data in Table VII the comene terpolymer. r bination of vanadium acetonylacetonate and zinc phos- 4. A method as in claim 3 in which the said diene is phorodithioate is a much more powerful regulator of mos-ethylidene-2-norborene lecular weight than the combination of vanadium oxytri- 5. A method as in claim .3 in .Which the saiddiene is chloride and zinc phosphorodithioate. This is reflected by dicyclopentadiene. 1 r the intrinsic viscosities and molecular weights which are 6. A method as in claim 3 inwhich the said dieneis approximately 50 percent lower, and the Brookfield vis- 1,4-hexadiene. Y cosities at 25 C. which are significantly lower than the 7. A method as in claim-1 in which the said vanadium C. viscosities (as in Examples 31, 33, 35 and 36) 60 salt is vanadium oxytrichloride. of the polymers made using vanadium oxytrichloride as 8. A method as in claiml in which the said vanadium the catalyst. salt is vanadium acetylacetonate. r

TABLE vII.-LIQUID TERPOLYMERS Y Example a7 38 39 .40 41 42 4a Diene ENB -ENB ENB Zinc 0,0-bis(4-methyl-2-pentyl) phosphorodithio- 3.0 3.0

ate (mmoles). Hydrogen, p s i g '5. 0 Yield, g so 70 Propylene, wt. percent 31 39 33 Iodine number 25 12 27 I.V 1. 33 0.19 0.13 Molecular weight, Mn---- 2,440 Brookfield viscosity at 25 0., poises 760 1,875

We claim: 7 a -s a 1. In a method of copolymerizing ethylene and an al- 7 9. A method asin claim 1 in which the ,said alkyalu pha-monoolefin, with or without a copolymerizable nonminum halide is ethylaluminum sesquichloride. e

10. A method as in claim 1 in which the said alkylaluminum halide is diisobutylaluminum chloride.

11. A method as in claim 1 in which the said regulator is a zinc compound.

12. A method as in claim 1 in which the said regular is a nickel compound.

13. A method as in claim 1 in which the said regulator is a chromium compound.

14. A method as in claim 1 in which the said regulator is a copper compound.

15. A method as in claim 1 in which the said regulator is an iron compound.

16. A method as in claim 1 in which the said regulator is a lead compound.

17. A method as in claim 1 in which the said regulator is a cadmium compound.

18. A method as in claim 1 in which the said regulator is a phosphorodithioate of formula (a).

19. A method as in claim 18 in which Y is hydrogen.

20. A method as in claim 18 in which Y is zinc.

21. A method as in claim 18 in which the said phosphorodithioate is zinc 0,0-bis(4 methyl-2penty1) phosphorodithioate.

22. A method as in claim 18 in which the said phosphorodithioate is nickel (II) 0,0-diethylphosphorodithioate.

23. A method as in claim 18 in which the said phosphorodithioate is chromium (1H) 0,0-diethyl-phosphorodithioate.

24. A method as in claim 19 in which the said phosphorodithioate is 0,0-2,2 dimethyltrimethylene hydrogen phosphorodithioate.

25. A method as in claim 18 in which the said phosphorodithioate is 0,0-diethyl hydrogen phosphorodithioate.

26. A method as in claim 18 in which the said phosphorodithioate is zinc 0,0-diethyl phosphorodithioate.

27. A method as in claim 1 in which the said regulator is a dithiocarbamate of formula (b).

28. A method as in claim 27 in which the said dithiocarbamate is zinc N,N-dibutyl dithiocarbamate.

29. A method as in claim 27 in which the said dithiocarbamate is copper (H) N,N-dibutyl dithiocarbamate.

30. A method as in claim 27 in which the said dithiocarbamate is iron (III) N-n-octadecyl-N-isopropyl dithiocarbamate.

31. A method as in claim 27 in which the said dithiocarbamate is lead (II) N-n-octadecyl-N-isopropyl dithiocarbamate.

32. A method as in claim 27 in which the said dithiocarbamate is chromium (II) N-n-octadecyl-N-isopropyl dithiocarbamate.

33. A method as in claim 27 in which the said dithiocarbamate is cadmium N,N-dibutyl dithiocarbamate.

34. A method as in claim 1 in which the said regulator is a dithiocarbonate of formula 35. A method as in claim 34 in which the said dithiocarbonate is zinc O-butyl dithiocarbonate.

36. A method of copolymerizing ethylene and propylene, with or without a copolymerizable non-conjugated diene, to form a copolymer of the said monomers which is liquid at ambient temperature, comprising contacting the said monomers in an inert organic solvent with vanadium oxytrichloride or vanadium acetylacetonate as a catalyst and an alkyl aluminum sesquichloride as a cocatalyst, in the presence of a polymerization regulator which is a zinc phosphorodithioate of the formula wherein R and R are alkyl groups.

37. A method as in claim 36 in which a copolymerizable non-conjugated diene is present.

38. A method as in claim 36 in which the said catalyst is vanadium acetylacetonate.

39. A method as in claim 36 in which hydrogen regulator is also present.

40. A method as in claim 36 in which the said diene is dicyclopentadiene.

41. A method as in claim 36 in which the said diene is S-ethylidene-Z-norbornene.

42. A method as in claim 36 in which the said diene is 1,4-hexadiene.

References Cited Technology (2nd edition, 1967), vol. 14, p. 295. JOSEPH L. SCHOFER, Primary Examiner A. L. CLINGMAN, Assistant Examiner US. Cl. X.R.

26080.78, 88.2 R, 94.4, 94.9 CB, 94.9 CC, 94.9 E 

